JPH05132540A - Curing agent for epoxy resin and curing of epoxy resin therewith - Google Patents

Abstract

PURPOSE:To obtain a cured product excellent in heat resistance, water resistance and mechanical properties, especially a cured epoxy resin useful for a multilayer printed wiring board by using a specified aromatic diamine as a curing agent for an epoxy resin. CONSTITUTION:An aromatic diamine of the formula (wherein R1 and R2 are each lower alkyl; X1 and X2 are H or halogen, and at least one of them is halogen) [e.g. 4,4'-methylenebis-(3-chloro-2,6-dimethylaniline)] is used as a curing agent for an epoxy resin. Although an aromatic diamine has heretofore been used as a curing agent for an epoxy resin, the obtained cured epoxy resin is insufficient in heat resistance and water resistance or is lacking in the shelf stability of a prepreg. By using this curing agent, a cured epoxy resin which is excellent in heat resistance, water resistance, etc., satisfactory in shelf stability and useful especially for a multilayer printed wiring board can be obtained.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a curing agent for an epoxy resin and a method for curing an epoxy resin. More specifically, an aromatic compound which is excellent in heat resistance, chemical resistance, electrical properties and mechanical properties and gives an epoxy resin cured product useful as a laminate, a fiber reinforced composite material, an adhesive for molding materials, especially a multilayer printed circuit board. The present invention relates to a diamine curing agent and an epoxy resin curing method using the same.

[0002]

2. Description of the Related Art Conventionally, 4,4'-methylenedianiline (MD) has been used as a curing agent for epoxy resins in the above applications.
A), 4,4'-methylenediorthochloraniline (M
OCA), 4,4'-diaminodiphenyl sulfone (D
Aromatic diamines such as DS) have been used. In recent years, there are strong demands for higher performance and improved reliability, and it is strongly desired to develop epoxy resin cured products with excellent heat resistance and water resistance, and curing agents that give prepregs with good storage stability in addition to heat and water resistance. It is rare. Further, MDA and MOCA are not preferable because they are suspected to be carcinogenic.

[0003]

A conventional epoxy resin cured product using an aromatic amine curing agent has problems in that it has insufficient heat resistance and water resistance, and lacks in storage stability of the prepreg. Further, development of a curing agent that is not toxic (carcinogenic) is desired.

[0004]

Means for Solving the Problems The present inventor has conducted diligent research to solve the above problems, and as a result, the aromatic diamine represented by the formula (1).

[0005]

[Chemical 2]

(Wherein R ₁ and R ₂ represent a lower alkyl group which may be the same or different, X ₁ and X ₂ represent a halogen atom or hydrogen, and at least one of them is a halogen atom) The present invention has been completed by finding that it is effective in solving the above problems when used as an agent. The curing agent and curing method of the present invention will be described in detail.

The aromatic diamine represented by the formula (1) undergoes dehydration condensation reaction between the corresponding 2,6-dialkyl-3-halogenoaniline or 2,6-dialkyl-3,5-dihalogenoaniline and formaldehyde. Therefore, it can be easily manufactured. The reaction is carried out in the presence of an acidic catalyst, based on 1 mol of formaldehyde, 2,6-dialkyl-
3-halogenoaniline or 2,6-dialkyl-3,5
-Dihalogenoaniline Normally, 1.0 to 3.0 mol, preferably 1.7 to 2.3 mol is used. Reaction temperature is usually 50
1 to 1 at a temperature of 150 to 150 ° C., preferably 90 to 120 ° C.
React for 0 hours. As the acidic catalyst, for example, hydrochloric acid, sulfuric acid or the like is used, and these are usually added in an amount of 0.
8 to 1.5 mol is used.

It is convenient to use water as the reaction solvent. After completion of the reaction, the reaction solution is put into an alkaline aqueous solution such as caustic soda or sodium carbonate for neutralization. The crystals precipitated after neutralization were filtered, washed thoroughly with water, and then dried to obtain an aromatic diamine as a target. Alternatively, after neutralization, a non-water-soluble organic solvent such as toluene or xylene is added and dissolved, and the organic layer is thoroughly washed with water, then the organic layer is separated from the aqueous layer, and the organic solvent is distilled off to obtain the desired product.

Specific examples of the aromatic diamine represented by the formula (1) include, for example, 4,4'-methylene-bis- (3-
Chloro-2,6-dimethylaniline), 4,4'-methylene-bis- (3-chloro-2,6-diethylaniline), 4,4'-methylene-bis- (3-chloro-2,
6-diisopropylaniline), 4,4'-methylene-
Bis- (3-chloro-2,6-dibutylaniline),
4,4'-methylene-bis- (5-chloro-2-ethyl-6-methylaniline), 4,4'-methylene-bis-
(3-chloro-2-ethyl-6-methylaniline),
4,4'-methylene-bis- (5-chloro-2-isopropyl-6-methylaniline), 4,4-methylene-bis (3,5-dichloro-2,6-dimethylaniline),
4,4'-methylene-bis- (3,5-dichloro-2,
6-diethylaniline), 4,4'-methylene-bis-
(3,5-dichloro-2-ethyl-6-methylaniline), 4,4'-methylene-bis- (3,5-dichloro-2,6-diisopropylaniline), 4,4'-methylene-bis- (3-Bromo-2,6-dimethylaniline), 4,4'-methylene-bis- (3-bromo-2,
6-diethylaniline), 4,4'-methylene-bis-
(5-bromo-2-ethyl-6-methylaniline),
4,4'-methylene-bis- (3-bromo-2-ethyl-6-methylaniline), 4,4'-methylene-bis-
(5-bromo-2-isopropyl-6-methylaniline) can be mentioned. In the present invention, for example, 4,4 '
A mixture of -methylene-bis- (3-chloro-2,6-diethylaniline) and 4,4'-methylene-bis- (3,5-dichloro-2,6-diethylaniline) can also be used.

Specific examples of the epoxy resin to which the curing agent of the present invention can be applied include bisphenol A type epoxy resin (reaction product of bisphenol A and epichlorohydrin),
Bisphenol F type epoxy resin, phenol novolac type epoxy resin, orthocresol novolac type epoxy resin, epoxy resin obtained from phenol aralkyl resin and epichlorohydrin, epoxy resin obtained from 4,4′-methylenedianiline and epichlorohydrin, aminophenols An epoxy resin obtained from epichlorohydrin, a brominated bisphenol A type epoxy resin, and a brominated phenol novolac type epoxy resin are included, but are not limited thereto.

The following components can be added to the curing agent of the present invention as needed. (1) Other curing agent for epoxy resin 4,4′-diaminodiphenyl sulfone, 3,3 ′,
5,5'-tetraethyl-4,4'-diaminodiphenylmethane, 3,3 ', 5,5'-tetramethyl-4,4
′ -Diaminodiphenylmethane, 4,4′-diaminobenzanilide, 3,3 ′, 5,5′-tetrabromo-
Ames test negative aromatic amines such as 4,4′-diaminodiphenylmethane, novaclacs such as dicyandiamide, phenol novolac, orthocresol novolac are used. The amount of the other curing agent for epoxy resin is 0 to 50% by weight based on the total amount of the curing agent due to heat resistance, mechanical properties, chemical resistance / water resistance, and workability.

(2) Curing accelerator Phenols, benzoic acid, salicylic acid, tertiary amines, B
F3 / amine complex salt, imidazoles, and phosphines are used. The compounding amount is 0.1 to 5% by weight in the curing agent. (3) Reinforcing agents and fillers Aluminum oxide, magnesium oxide, calcium carbonate, silica powder, mica powder, carbon black, antimony trioxide, molybdenum disulfide, fibrous reinforcing agents and fillers such as glass fiber, carbon fiber, Aramid fiber etc. The amount of these reinforcing materials and fillers used depends on the application, but can be compounded up to 0 to 70% by weight in the resin composition.

(4) Colorant Inorganic or organic pigments can be blended as required. In the curing agent of the present invention, the ratio of the active hydrogen equivalent of the diamine represented by the formula (1) is usually 0.5 to 1.5 with respect to 1 equivalent of the above various epoxy resins, but 0.7 to 1 It is preferable to mix them so as to be 0.2.

The epoxy resin, the curing agent of the present invention and other optional components are blended by heat-melt mixing or kneading using a roll, a kneader or the like, or dissolved in a solvent such as methyl ethyl ketone, ethyl cellosolve or dimethylformamide. Prepare an epoxy resin varnish. The formulation of the epoxy resin and the curing agent of the present invention and other optional components is usually 10
It is cured by heating at 0 to 200 ° C. to give an epoxy resin cured product having excellent heat resistance, water resistance and mechanical properties. Further, the prepared epoxy resin varnish is impregnated into a base material such as glass cloth and carbon fiber according to a conventional method, and the epoxy resin is semi-cured by heating and drying the epoxy resin prepreg.

[0015]

EXAMPLES The present invention will be described in more detail with reference to synthesis examples and examples.

Synthesis Example 1 500 ml of water and 52 g of 35% hydrochloric acid are added to a 1 liter four-necked flask equipped with a stirrer, a thermometer and a reflux condenser. Then 92 g of 3-chloro-2,6-diethylaniline was added to 4
Add dropwise at 0 ° C or lower. Next, 37% formalin aqueous solution 23
g is added dropwise over 2 hours while maintaining the reaction temperature of 50 to 55 ° C. Then, it takes 2 hours to gradually raise the temperature to 90-95 ° C. and react at the same temperature for 3 hours. The slurry liquid of the obtained reaction product is cooled to 40 ° C., and 107 g of a 20% aqueous sodium hydroxide solution is added dropwise at 40 ° C. or lower to neutralize. Then, it was filtered, washed with water repeatedly, and dried to obtain white crystals. 4,
The amount of 4′-methylene-bis- (3-chloro-2,6-diethylaniline) was 92 g (yield 97.0%), and the result of analysis by gas chromatography showed that the purity was 99.0%.
mp. 87-90 ° C. The desired product was confirmed by NMR and mass spectrum.

Synthesis Example 2 3-Chloro-2,6-diethylaniline was converted into 3-chloro-
Synthesis Example 1 except that 78 g of 2,6-dimethylaniline was used.
In the same manner as above, a new white crystalline 4,4'-methylene-bis- (3-chloro-2,6-dimethylaniline) was obtained. Yield 78.8 g (yield 97.5%), purity 98.
3% (GC). ¹ HNMR (CDCl ₃ ) δ (ppm): 2.1 (s, 6H, Ph-CH ₃ ) 2.3 (s, 6H, Ph-CH ₃ ) 3.6 (s, 4H, NH ₂ ) 4. 0 (s, 2H, Ph- CH 2 -Ph) 6.6 (s, 2H, Ph-H) mp173~177 ℃

Synthesis Example 3 Synthesis Example 3 except that 95 g of 3,5-dichloro-2,6-dimethylaniline of 3-chloro-2,6-diethylaniline and 25 g of 37% formalin aqueous solution were changed.
Reaction and post-treatment were carried out in the same manner as in 1 to give 4,4′-white crystals.
Methylene-bis- (3,5-dichloro-2,6-dimethylaniline) was obtained. Yield 94.1 g (yield 96.0%), purity 97.8%
(GC).

Example 1 100 g of Epicoat 828 (bisphenol A type epoxy resin manufactured by Yuka Shell Epoxy Co., Ltd.) and 4,4'-methylene-bis- (3-chloro-2, obtained in Synthesis Example 1)
50 g (equivalent) of 6-diethylaniline was melt-kneaded at 100 ° C. After defoaming, the mixture was poured into a metal mold heated to 120 ° C., and heat-cured in an oven at 120 ° C. for 2 hours, 150 ° C. for 3 hours, and 180 ° C. for 5 hours. A test piece was cut out from the cured molded product and tested for glass transition temperature, water resistance and mechanical properties. The results are shown in Table 1.

Example 2 Curing was carried out in the same manner as in Example 1 except that the diamine was changed to 4,4'-methylene-bis- (3-chloro-2,6-dimethylaniline) obtained in Synthesis Example 2. Was done. The test results of the cured product are shown in Table 1.

Example 3 4,4'-methylene-bis- (3,5-dichloro-2,6-dimethylaniline) obtained in Synthesis Example 3 from diamine was prepared.
Curing was performed in the same manner as in Example 1 except that
The test results of the cured product are shown in Table 1.

Comparative Examples 1 and 2 Curing was carried out in the same manner as in Example 1 except that methylene dianiline (Comparative Example 1) and methylene diorthochloraniline (Comparative Example 2) were used as diamines. The test results of the cured product are shown in Table 1.

Example 4 YDB-500 [Toto Kasei Co., brominated bisphenol A type epoxy resin] 70 g, EOCN103S [Nippon Kayaku Co., orthocresol novolac type epoxy resin] 30 g, 4,4'-methylene-bis 15 g of-(3-chloro-2,6-diethylaniline), 1.4 g of dicyandiamide, 2-ethyl-4-methylimidazole.
2 g was dissolved in 50 g of methyl ethyl ketone and 50 g of dimethylacetamide to prepare an epoxy resin varnish. This varnish was impregnated with glass cloth 7628 / AS431 (manufactured by Asahi Shabel Co.) and dried at 150 ° C. for 8 minutes to prepare a prepreg. Eight sheets of this prepreg are overlaid, 0.035 mm thick copper foil is overlaid on both sides, 180 ° C, 40 kg /
A copper-clad laminate having a thickness of 1.6 mm was produced by press molding for 120 minutes under the condition of cm ² . The prepreg was tested for gel time, change in gel time with time, water absorption and solder heat resistance. The test results are shown in Table 2.

Example 5 A prepreg and a prepreg were prepared in the same manner as in Example 3 except that the diamine was replaced by 4,4'-methylene-bis- (3-chloro-26-dimeteraniline) obtained in Synthesis Example 2. A copper-clad laminate was prepared and evaluated. The evaluation results are shown in Table 2. 0
Comparative Example 3 A prepreg and a copper clad laminate were prepared and evaluated in the same manner as in Example 3 except that methylenediorthochloroaniline was used instead of diamine. The evaluation results are shown in Table 2.

Comparative Example 4 A prepreg and a copper clad laminate were prepared and evaluated in the same manner as in Example 3 except that only dicyandiamide was used as the curing agent. The evaluation results are shown in Table 2.

[0027]

[Table 1]

* 1 Measured using a gel time tester manufactured by Yasuda Seiki. * 2 Measured using a TMA tester manufactured by Seiko Denshi Kogyo. * 3 to * 6 Measured according to JIS K 6911.

[0029]

[Table 2]

[0030]

The epoxy resin curing agent of the present invention gives an epoxy resin cured product excellent in heat resistance, water resistance and mechanical properties, and is particularly excellent in heat resistance and water resistance and also in storage stability of prepreg. It is useful as an epoxy curing agent for laminates.

Claims (2)

[Claims] 1. An aromatic diamine represented by the formula (1): (Wherein R ₁ and R ₂ represent lower alkyl groups which may be the same or different, X ₁ and X ₂ represent a halogen atom or hydrogen, and at least one is a halogen atom) Hardener. 2. A method for curing an epoxy resin, which comprises using the curing agent for an epoxy resin according to claim 1.